The Green Bank Telescope in Green Bank, West Virginia, stands near the center of the National Radio Quiet Zone, where limited transmissions protect faint cosmic signals. Beginning regular science operations in 2001 and operated since 2016 by the independent Green Bank Observatory, it is the world’s largest fully steerable radio telescope. Its off-axis design, active surface, and wide frequency range make it unusually flexible for work from pulsars and molecular astronomy to hydrogen mapping and planetary radar support. Built after the 1988 collapse of the earlier 300 Foot Radio Telescope, it has produced major discoveries, remained central to American radio astronomy, and continues to serve research, education, outreach, and Breakthrough Listen.